code: def test_hkernel_length_fir_lambda():
      """Test the hrf computation."""
      tr = 2.0
  
      h = _hrf_kernel("fir", tr, fir_delays=np.arange(4))
      assert len(h) == 4
  
      h = _hrf_kernel(lambda tr, ov: np.ones(int(tr * ov)), tr)
      assert len(h) == 1
  
      h = _hrf_kernel([lambda tr, ov: np.ones(int(tr * ov))], tr)
      assert len(h) == 1
  
imports: import warnings
  import numpy
  import pytest
  from numpy.testing import assert_almost_equal, assert_array_almost_equal, assert_array_equal
  from nilearn.glm.first_level.hemodynamic_models import _calculate_tr, _hrf_kernel, _regressor_names, _resample_regressor, _sample_condition, compute_regressor, glover_dispersion_derivative, glover_hrf, glover_time_derivative, orthogonalize, spm_dispersion_derivative, spm_hrf, spm_time_derivative
label_desc: Use image node_id 17 for calling a global function with example usage: test_hkernel_length_fir_lambda() without return types